基于缺口应力法的转向架焊接接头疲劳性能分析

Fatigue Performance Analysis of Bogie Welded Joints Based on Notch Stress Method

缺口应力法作为焊接结构疲劳设计的新方法以其较高的准确性而得到越来越广泛的应用。鉴于铁道车辆焊接结构尚未建立可靠的缺口疲劳寿命曲线,根据当前转向架焊接接头疲劳试验所提供的数据进行了缺口疲劳分析。疲劳试验名义应力数据源自构架常用材料S355J2所生产的2种焊接接头试样,包括低缺口效应的对接接头和高缺口效应的十字角接头。采用经验公式法和有限元方法对焊接接头的焊趾焊根缺口应力集中系数进行了分析,联合疲劳试验下的名义应力数据建立了转向架焊接接头的缺口疲劳寿命曲线。通过与IIW标准推荐的缺口疲劳曲线FAT225相比较,该曲线具有相当的疲劳等级和更小的曲线斜度;同时从差异系数的角度证明了缺口应力法比名义应力法具有更小的分散性。

The notch stress method,as a new method for fatigue design of welded structure,is widely used for its higher accuracy.Considering the absence of a reliable notch fatigue life curve in the vehicle welded structure,the paper,based on the data provided by the current fatigue test of bogie welded joints,carried out the notch fatigue analysis.Nominal stress data of fatigue test were derived from two welded joint specimens produced by common bogie materials S355J2 in the framework,including butt joints with low notch effect and cruciform joints with high notch effect.By adopting an empirical formula method and a finite element method,the paper analyzed the notch concentration factors of weld toe and weld root and established the notch fatigue curve of bogie welded joints by combining with nominal stress data in the fatigue test.By making a comparison with the notch fatigue curve FAT225 recommended by IIW standard,this curve has a considerable fatigue class and smaller slope of curve.Moreover,it proved that the notch stress method has smaller dispersibility than the normal stress method,from the perspective of diversity factor.